Porter-Cable 4212 - Manual (Page 14)

14
HALF-BLIND DOVETAIL BITS
The difference in using alternate bits and standard
bits in making half-blind dovetails is in the depth-of-
cut.
DOVETAIL BIT
WOOD FOR HALF-BLIND JOINT
HALF-BLIND TEMPLET
TEMPLET GUIDE
ROUTER SUB BASE
DEPTH OF CUT FOR A HALF-BLIND JOINT
Fig. 19A
ROUTER SUB BASE
TEMPLET GUIDE
DOVETAIL BIT
DOVETAIL BIT DIAMETER
WHEN THE DIAMETER OF THE ROUTER
BIT IS GREATER THAN THE INSIDE
DIAMETER OF THE TEMPLET GUIDE
THERE IS A MINIMUM DEPTH OF CUT
21/32"
Fig. 18A
THROUGH-DOVETAIL BIT COMBINATIONS (READILY AVAILABLE)
DOVETAIL BIT DIAMETER STRAIGHT BIT DIAMETER
3/4"
5/8"
9/16"
17/32" 3/16"
5/16"
3/8"
13/32"
ALTERNATE ROUTER BITS
You are not limited to using the router bits supplied with your jig. Other router bits can be used to produce a different
look or to work with thicker woods. Using alternate bits can help you produce more advanced joints (inlayed
dovetails, etc.). Since 1/2" shank bits are stronger and are much less prone to deflection than the 1/4" shank bits,
we recommend that you use the 1/2" shank bits with the 4210 and 4212 dovetail jigs, and with the 4211 and 4213
accessory kits.
THROUGH-DOVETAIL BITS
If you choose to purchase alternate through-dovetail bits, keep in mind the following:
1.
The dovetail bit must have a 7
° angle. This angle matches the tapered fingers used to guide the straight bit.
2. The sum of the diameters of the dovetail and straight bits must equal 15/16". For example, a 5/8" dovetail bit
must have a 5/16" straight bit - the sum of both equalling 15/16".
3. The length of the cutter determines the maximum thickness of wood that can be cut. The length of the cutter
on the dovetail bit is the maximum thickness of the pin board. The length of the cutter on the straight bit is the
maximum thickness of the tail board. If your bits have 1" cutters, you can make through-dovetails with 1" thick
boards.
4. Purchase bits that will not cut into the template guides. The template guide used with the dovetail bit has an
inside diameter of 21/32". Use bits that will fit into this dimension. Some larger bits might work, but with
minimal depth (Fig. 18A).
5. The inside diameter of the template guide used with the straight bit is 17/32". Use straight bits that are smaller
than that dimension.